Limit switch



Oct- 10, 1933- G. A. HALFvARsoN LIMIT SWITCH Filed May 27. 1929 INVENTOR Gusaf A.Halvarson Patented Oct. 10, 1933 PATE-Nr oFF LIMIT Gustaf' A. Halfvarson,

SWITCH Verona, Pa., assignoi" to Westinghouse Electric & Manufacturing Com- Dany, a corporation of Pennsylvania` Application MayV 27, 1929. Serial No.- 366,285

7 Claims.

switch of the above mentioned Ytype that shallhave an actuating` member thatmay be operated by a cam passing thereacross.

Aiurther object ofrny invention istoprovide a switch oftheabovementionedtype with restraining means that shall prevent the movement of thev switch arm fromeither off its positions after the spring toggle has passed beyond its over-center position and until the actuating means has reached al predetermined position.

Difficulty has been experienced heretofore in cam-actuated switchesV because of the straining of the various members when the cam that passes over the actuating member is` bent or is out of adjustment and thereby forces the actuating member beyond the switch-,closed position;

In practicing my invention, Iprovide a springtoggle connection between'a rocker membery and an actuating member that is soassociatedtherewith that the rocker member may pass beyond theswitch-actuated position to a position below theY supporting structure of the rocker member. In such construction, when the cam is out of adjustment, the actuating member may be moved beyond the switchposition and, as this movement is not limited until the member has passed below its supporting structure, the supporting structure itself must thereby take the strain of the cam, provided it is bent from its normal position a suicient amount.

It is, therefore, a further object of my invention to provide an actuating member for arswitch of the above-mentioned type thatmay be moved out of the path of an actuating cam beyondrthe switch position and below the support for the said actuating member.

It is a still further object of my invention to provide a contact finger for aswitch mechanism that shall be simple in construction andlcharacv terized by the ease with which it may be removed and renewed. r

With these principles and objectsin mind, my invention will best be understood by referring to the accompanying specication, taken-incon- 50 junction with the drawing, wherein Fig; 1 is a View, in elevation, ofv a switch mech'- anism embodying my invention;

Fig. 2 is a view in section, of the structure shown in Fig. l, taken along the linen-II;

Fig. 3 is a sectional view ofthe structure shown in Fig. 1, taken along thel line III-III;

Fig.,4 is a View in section, of the structure of Fig. 1, taken along' the line'IV-IV Fig. 5is a View in elevation, of a contact finger oshown in Figs. 1 and 2, and

Fig.; Gis' an. endfview ofthe-contact'nger in Fig. 5.

My invention: comprises, .inl generahan vinsulat` ing base. l; and .uprights 2 and 3; fastened: thereto by ineanaoi' boltsfiand'5. The-base 1 isalsol the means of supporting contact:V members; 6: through which the' circuitis; completediby thief bridging member. 7..

upperk ends. An actuating member: QfWhiQ-h is', journal-led in the'. uprights andf betweene-the'; base and the shaft'i, comprises.l a crankportion 10, and the axialportion lesupporting ani in` sulating spool 11 upon` whichthe bridging' mem-- ber 7 is clamped and by which thei'member 7-` is insulatedfrom the actuatingv member; anclffrom the uprights 2 and3.

Referring to Fig. 4, the. endfof, thegactuating: member 9i adjacent to the uprightZ', which end constitutes" aA part of thezcranlc thereof:, ispro vided withacurvedtsurface having arr indented portion 121 that` forms' shoulders.:A 13` amiral` Latclies 15V and 16are pivotallyr sup-ported onft'he inner sideI of' the upright4 2f byf'pins: 1 '73A and: 183 A- spring 21n connectsv the latches; 15 1.6 to bias them toward each other; ther-actuating; member gvisrrotatively moved, the; latchesA slide over the-surface thereof until one'o themen.- gages one of the shoulders 13. andl 14f t0:1atoh the member inthatlpos-ition.. r

A rocker 22 is mountedl on the shaft 8 andis projections 32` fromfwasher 29 whichvslides; onza spring-toggle link 3.3. A washer 35fon the lower end of:` the link 33 is disposed in an openingfl 30 in the lower or crank pin section of the crank portion 10. Projections 34ron1thewasher Sengage in a groove 36 formed in the lower side of'A said crank pin section.. By so connectingy the spring-togglev link 33` tov theactuating. member and the rocker, itl maybe removed' therefrom, as aunit,y byy merelyv twisting` it outof the` groove 36 andthe openingsl.

The side ofthe extension 28loiv therrocker.' 22 adjacent to the upright' 2-is provided'=vvithA aprojection' 37 aboveV thel openingy 31- thereofto' act as a-camV toengage one'of the latches 15 and 16, as the rockerismoved fromvl eithery of its posi'- tions.

-Extensions 38 are provided atthesid'cs-'ofY the extension'28 whichv are of such'length and shape that they engage the crank of the actuating member 9 just after the projection 37 has released the latch 15 or the latch 16. The construction provides a positive engagement between the rocker 22 and the actuating member 9 to initially move it from either of its positions.

Such construction is desirable to assure the initial movement of the contact members, which may resist the actuating `forceexerted by the toggle link 33, because of oxidation of the metal of the said contact members, or because of resistance from any other cause.

Stops 39 are provided on the inner side of the upright 2 for engaging the crank 10 of the actuating member 9 to thereby position the bridging member 7 to either its on or its olf position.

' Each contact member 6, comprises an angular supporting member 40 that is fastened to the El?) base by a bolt 41 and is connected to an electric circuit through a bolt 42. A slot 43 in the top and slots 44 in the sides of the support 40 are provided to support a ringer 45 thereon. The nger 45 comprises a conducting member, bent to the shape shown in Figs. 5 and 6, and has an aperture therein through which a rivet 46 extends. The rivet 46 has an enlarged head on each-of its ends that retains it on the finger 45, washers 47 and 48 and a spring 49 being mounted on the rivet.

The central portion of the bottom end 5l of the finger 45 is cut away to form two projections 52. The projections 52 engage the slots 44 of the supporting structure 40 after the rivet 46 has been inserted in the slot 43 thereof. Such construction permits outward movement of the lingers 45 caused by movement of the bridging member 7 between them. If it is desired to release a nger 45 from the supporting member 40 it is only necessary to move it inwardly beyond its normal position. This movement disengages the projections 52 from the slots 44 and permits the rivet 46 to be moved upwardly out of the slot 43. Thus, a small inward and upf ward movement removes the contact ringer 45 from its supporting member 40.

It is to be understood that, while only a single set of contact members is shown in the drawing, any number may be employed by lengthening the supporting shaft 8, the base 2 and the axis 19 of the actuating member 9 and by providing additional contact fingers 6, bridging members 'l and insulating spools l1. 'When the words on and off have been employed, it is to be understood that, if a plurality of contacts are employed, some may be moved to the one or to the other position at each operation or all may be either completing a circuit or opening one.

The operation of my switch will now be described.

Assuming the switch to be in the closed position shown in Fig. 2 and an actuating cam 53 to be moving across the rollers 26, it will be noted that the left-hand roller will be first engaged by the cam and movedV downwardly to rotate the rocker 22 in counterclockwise direction. As pointed out above, the possibility of such movement beyond switch-closed position is one of the objects of the invention and is obtained through the association of the structures hereinbefore described.

Continued movement of the cam 53 causes the rocker 22 to move in aclockwise direction by engagement of the cam 53 with the right-hand roller 26. The clockwise movement moves the extension 28 in a clockwise direction, thereby stressing the spring of the toggle link 33 and causing it to be moved to its over-center position.

In such position, the actuating member 9 should be moved to operate the bridging member 'l but, as pointed out above, this is prevented by the engagement of the latch 15 with shoulder 13 of the actuating member 9. Continued movement of the rocker 22 moves the projection 37 thereon into engagementwith the latch l5 to move it out of engagement'with the projection 13 after the spring toggle 33 has been compressed a predetermined amount.

This release permits the actuating member 9 to move the bridging member 7 out of engagement with the ngers 6. At the time that thelatch l5 is disengaged iromthe projection 13, the extension 38 has moved or is about to move into engagement with the crank of the actuating member 9 to apply a force thereto to initially move the bridging member 7 from engagement with the fingers 45.

In the closing operation, the same cycle of stressing the toggle, releasing the latch and positively moving the actuating armA 9, is passed through, and the actuating arm 9 is then latched in the closed position, as shown.

It will thus be seen that I have'provided a tumbler-type switch that is latched in either of its positions and is thereby moved from or to either of its positions only after the biasing means to move it has been stressed a predetermined amount. The latches employed to retain the mechanism against the bias has an additional utility of retaining the contact members in their desired positions until the latch has been released, through the movement of the rocker employed to actuate the switch.

ies

My invention is further novel in vso associating the rocker with the actuating arm that the former may be moved to either side of its normal position out of the path of the actuating cam and below its supporting structure. My contact structure is also novel in that a contact ringer,

which may become damaged from wear, is very simple in construction and may be removed by simply pushing it inwardly and upwardly.

While I have shown but a single embodiment of my invention, it is to be understood that additions, subtractions, omissions and substitutions `may be made therein without departing from the switch member, a link carrying a compression spring connecting said switch member with said actuating member, said spring biasing said switch member to one position until the actuating member has passed the center of its path of travel, and then biasing said switch member to the second position, and means for releasing said latch after the spring has biased the switch member to said second position.

2. A switch structure including a switch member, means for latching said member in either.v

of two positions, an actuating member for said switch member, a link carrying a compression spring connecting said switch member with said actuating member, said spring biasing said switch member to one position until the actuatingY member has passed the center of its path of travel, and then biasing said switch member to the second position, and means for releasing said latch after the spring has biased the switch member to said second position, said actuating member being movable beyond the positions to which it must move to change the position of the switch member.

3. A cam operated switch structure including a pivoted switch-actuating member, a rocker member pivoted about an axis spaced from the axis of the actuating member, the rocker member having a pair of arms adapted to be actuated by a cam, one of said arms being arranged to be engaged by the cam when the rocker member is in the iirst position to move the rocker member to the second position and the other arm being arranged to be engaged by the cam when the rocker member is in the second position to move the rocker member to the rst position, and an overcenter spring connection between the rocker and the actuating member exerting a bias on the latter in a direction toward the axis thereof, said spring connection being movable past the axis of the actuating member by movement of the rocker from a rst position to a second position to move the actuating member from one position to another, said spring connection biasing the rocker to the rst position when the actuating member is in said one position and to the second position when the actuating member is in said other position, and said rocker member being movable beyond said iirst and second positions against the bias of said spring connection to avoid damage to the switch structure in case of misalignment thereof with respect to the path of the cam.

4. In a cam operated switch-actuating structure, the combination of a switch-actuating member movable to rst and second positions, a pivoted rocker member movable to first and second positions thereof for moving the actuating member to rst and second positions, respectively, the rocker member having a pair of arms adapted to be actuated by a cam, one of said arms being arranged to be engaged by the cam when the rocker member is in the first position to move the rocker member to the second position and the other arm being arranged to be engaged by the cam when the rocker member is in the second position to move the rocker member to the first position, and spring means connecting the rocker member and the actuating member exerting a bias on the latter in a direction toward the axis thereof whereby the rocker actuates the actuating member, said rocker member being movable beyond the iirst and second positions thereof to avoid damage to the switch actuating structure in case of misalignment thereof with respect to the path of the cam, and said spring means biasing the rocker member to the first position thereof when the actuating member is in iirst position and to the second position thereof when the actuating member is in the second position.

5. A switch structure including a pivoted switch-operating member, means for latching said switch-operating member in either one of two positions, an actuating member pivoted about an axis spaced from the axis of the switch-operatng member, an over-center spring connection between the switch-operating member and the actuating member, said spring connection having only a single line of action which is moved across the axis of the switch-operating member by movement of the actuating member, so that the spring connection biases the switch-operating member to its previously assumed position during the initial movement of the actuating member and to its new position after crossing the axis of the switch-operating member, means for releasing the latching means after the spring connection biases the switch-operating member to its new position, and means carried by the actuating member for moving the switch-operating member immediately after said latching means is released.

6. A switch-operating structure including a pivoted switch-operating member movable to closed-circuit and open-circuit positions, an actuating member for moving the switch-operating member, an over-center spring connection between the switch-operating member and the actuating member exerting a bias on the former in a direction toward the axis on which the switchoperating member is pivoted, said parts being so arranged that the line or direction of said bias is moved from one side of said axis to the other by movement of the actuating member and so that the spring connection biases the switchoperating member to its previously assumed position during the initial movement of the actuating member and to its new position after the line of bias has crossed the axis of the switch-operating member, a latch for holding the switch-operating member in one position, means for releasing said latch after the spring connection biases the switch-operating member to the other position, and means carried by said actuating member for moving said switch-operating member by positive engagement just after said latch is released.

7. A switch structure including a switch member movable to open and close the circuit, a pivoted switch-operating member movable to closedcircuit and to open-circuit position, an actuating member for moving said switch-operating member, an over-center spring connection between the switch-operating member and the actuating member, said spring connection exerting a bias on said switch-operating member in a direction toward the axis on which said switch-operating member is pivoted, said parts being so arranged that the line or direction of said bias is moved from one side of said axis to the other by movement of the actuating member and so that the spring connection biases the switch-operating member to its previously assumed position during the initial movement of the actuating member and to its new position after the line of bias has crossed the axis of the switch-operating member, a latch for holding the switch member in one position, means for releasing said latch after the spring connection has moved to bias the switchoperating member to the other position, and means operable by said actuating member for positively moving said switch member just after said latch is released.

GUSTAF A. HALFVARSON. 

